Been noticing that the big battery indicator is at two or three bars when first started in morning, but after a few miles jumps up to full charge. This is a 2011 model used and AFAIK, has not had any big or 12V battery problems. Should I be concerned and save my pennies towards a new big battery, or start kicking late model Prius tires for car replacement and let next owner replace battery(s)? Granted $3-4K for big battery (last cost I heard of) is way less than new car, and my car has had no (knock on wood) repairs other than recalls and coolant replacements as required by the owners manual. Thanks.
Was it displaying more bars when parked the night before? When you say "jumps", do you mean a sudden climb? That sounds a little troubling. How many miles btw?
Have you had the car long enough to get an idea if this behavior is a sudden change? You're at the end of the traction battery warranty, so it would be wise to be ready. Then again, it could last for several more years. @Mendel Leisk asked a very good question. If it jumps from 2 bars to 6 quickly, that's a sign that it has lost significant capacity and it nearing the end of its life. On the other hand, if you live at the top of a hill, it might be normal to have used up some battery power getting home and then it would charge pretty quickly when you leave and go back down the hill. Since it's not throwing codes yet, a Prolong grid charger could give you quite a few more years before having to replace the battery.
When I have 2 bars and get on the highway immediately, I get 6 bars after 5 to 6 hwy miles and that’s normal. Or 45mph stretches I can get 6 bars with 4 miles driven. It’s supposed to charge up like that
Climb is not sudden, just a slow orderly progression over maybe 6-8 miles, city or highway. Have had the car for 7+ years but its just been lately that I have noticed the low bars in morning start, then ratcheting upwards. When I did engineering work with Ni-Cds (big battery not same technology I know), batteries that took sudden charge jumps or had short run times, sometimes was indicator of battery end of life.
same is true for prius, but the indicator would continue to fluctuate while driving. maybe just a weak cell
Can you recall what the charge was like, the night before a two-bar morning. Did it dropped overnight?
When put in garage at night, battery shows full or one bar below full. Of course in summer the AC really ran the battery down if stopped for a few minutes, then engine would come on to recharge battery.
Unless you're leaving your car on, the a/c is not running the battery down overnight. I've sat with a/c running and it will be about 10-15 minutes before the battery gets low enough for the engine to kick in. I have only done that a few times but it's been the same each time.
It sure sounds like something's going on with your traction battery. Re-balancing it may give it years of life. Or put in a new one and be done with it. But do some diagnostic tests before spending all that money.
